Showing papers on "Photonic-crystal fiber published in 2007"
TL;DR: New formulas providing comprehensive approximations of the optical properties of silica glass are proposed between 7 and 50 microm, which are consistent with experimental data and substantially extend the spectral range of 0.21-7 microm covered by existing formulas and can be used in various engineering applications.
Abstract: We thoroughly and critically review studies reporting the real (refractive index)
and imaginary (absorption index) parts of the complex refractive index of silica glass
over the spectral range from 30 nm to 1000 μm The general features of the optical
constants over the electromagnetic spectrum are relatively consistent throughout the
literature In particular, silica glass is effectively opaque for wavelengths shorter
than 200 nm and larger than 35-40 μm Strong absorption bands are observed (i) below
160 nm due to the interaction with electrons, absorption by impurities, and the presence
of OH groups and point defects; (ii) at ~273-285, 35, and 43 μm also caused by OH
groups; and (iii) at ~9-95, 125, and 21-23 μm due to SiOSi resonance modes of
vibration However, the actual values of the refractive and absorption indices can vary
significantly due to the glass manufacturing process, crystallinity, wavelength, and
temperature and to the presence of impurities, point defects, inclusions, and bubbles,
as well as to the experimental uncertainties and approximations in the retrieval
methods Moreover, new formulas providing comprehensive approximations of the optical
properties of silica glass are proposed between 7 and 50 μm These formulas are
consistent with experimental data and substantially extend the spectral range of 021-7
μm covered by existing formulas and can be used in various engineering applications
882 citations
Book•
01 Dec 2007TL;DR: In this article, the authors present a detailed analysis of planar optical waveguide and a step-index fiber model for optical fiber communication and demonstrate the properties of a step index fiber.
Abstract: 1. Introduction 2. Basic optics 3. The optical fiber 4. Ray analysis of planar optical waveguide 5. Graded index optical fibers 6. Material dispersion 7. Planar waveguides 8. Characteristics of a step-index fiber 9. Graded Index fibers 10. Waveguide dispersion and design considerations 11. Sources for optical fiber communication 12. Detectors for optical fiber and communication 13. Fiber optic communication system design 14. Optical fiber Amplifiers 15. Dispersion compensation and chirping phenomenon 16. Optical solitons 17. Single-mode fiber optic components 18. Single mode optical fiber sensors 19. Measurement methods in optical fiber: I 20. Measurement methods in optical fibers: II 21. Periodic interactions in waveguides 22. Ray equation in Cartesian coordinates 23. Ray paths 24. Leaky modes.
843 citations
TL;DR: Generation and guidance of a three-octave spectral comb, spanning wavelengths from 325 to 2300 nanometers, in a hydrogen-filled hollow-core photonic crystal fiber, is demonstrated, opening up a robust and much simplified route to synthesizing attosecond pulses.
Abstract: Ultrabroad coherent comb-like optical spectra spanning several octaves are a chief ingredient in the emerging field of attoscience. We demonstrate generation and guidance of a three-octave spectral comb, spanning wavelengths from 325 to 2300 nanometers, in a hydrogen-filled hollow-core photonic crystal fiber. The waveguidance results not from a photonic band gap but from the inhibited coupling between the core and cladding modes. The spectrum consists of up to 45 high-order Stokes and anti-Stokes lines and is generated by driving the confined gas with a single, moderately powerful (10-kilowatt) infrared laser, producing 12-nanosecond-duration pulses. This represents a reduction by six orders of magnitude in the required laser powers over previous equivalent techniques and opens up a robust and much simplified route to synthesizing attosecond pulses.
505 citations
TL;DR: As potential applications of the all-PCF interferometer, strain sensing is experimentally demonstrated and ultra-high temperature sensing is proposed.
Abstract: We propose simple and compact methods for implementing all-fiber interferometers. The interference between the core and the cladding modes of a photonic crystal fiber (PCF) is utilized. To excite the cladding modes from the fundamental core mode of a PCF, a coupling point or region is formed by using two methods. One is fusion splicing two pieces of a PCF with a small lateral offset, and the other is partially collapsing the air-holes in a single piece of PCF. By making another coupling point at a different location along the fiber, the proposed all-PCF interferometer is implemented. The spectral response of the interferometer is investigated mainly in terms of its wavelength spectrum. The spatial frequency of the spectrum was proportional to the physical length of the interferometer and the difference between the modal group indices of involved waveguide modes. For the splicing type interferometer, only a single spatial frequency component was dominantly observed, while the collapsing type was associated with several components at a time. By analyzing the spatial frequency spectrum of the wavelength spectrum, the modal group index differences of the PCF were obtained from 2.83×10-3 to 4.65 ×10-3 . As potential applications of the all-PCF interferometer, strain sensing is experimentally demonstrated and ultra-high temperature sensing is proposed.
418 citations
TL;DR: In this article, a fiber-optic strain sensor is demonstrated by using a short length of polarization-maintaining photonic crystal fiber (PM-PCF) as the sensing element inserted in a Sagnac loop interferometer.
Abstract: A fiber-optic strain sensor is demonstrated by using a short length of polarization-maintaining photonic crystal fiber (PM-PCF) as the sensing element inserted in a Sagnac loop interferometer. Spectrum shift in response of strain with a sensitivity of 0.23pm∕μe is achieved, and the measurement range, by stretching the PM-PCF only, is up to 32me. Due to the ultralow thermal sensitivity of the PM-PCF, the proposed strain sensor is inherently insensitive to temperature, eliminating the requirement for temperature compensation.
415 citations
TL;DR: To the knowledge, this work presents the highest pulse energy ever extracted from fiber based femtosecond laser systems, and a nearly 2 orders of magnitude higher repetition rate than in previously published millijoule-level fiber CPA systems.
Abstract: We report on an ytterbium-doped fiber chirped-pulse amplification (CPA) system delivering millijoule level pulse energy at repetition rates above 100 kHz corresponding to an average power of more than 100 W. The compressed pulses are as short as 800 fs. As the main amplifier, an 80 μm core diameter short length photonic crystal fiber is employed, which allows the generation of pulse energies up to 1.45 mJ with a B-integral as low as 7 at a stretched pulse duration of 2 ns. A stretcher-compressor unit consisting of dielectric diffraction gratings is capable of handling the average power without beam and pulse quality distortions. To our knowledge, we present the highest pulse energy ever extracted from fiber based femtosecond laser systems, and a nearly 2 orders of magnitude higher repetition rate than in previously published millijoule-level fiber CPA systems.
291 citations
TL;DR: In this paper, the microhole collapse property of different photonic crystal fibers (PCFs) and its effect on the splice loss using an electric arc fusion splicer was investigated, and a guideline for splicing these PCFs and conventional single-mode fibers (SMFs) was proposed.
Abstract: We investigate the microhole collapse property of different photonic crystal fibers (PCFs) and its effect on the splice loss using an electric arc fusion splicer. The physical mechanism of the splice loss for different kinds of PCFs is studied, and a guideline for splicing these PCFs and conventional single-mode fibers (SMFs) is proposed. We demonstrate a low-loss fusion splicing of five different PCFs with SMFs, including large-mode PCF, hollow-core PCF, nonlinear PCFs, and polarization-maintaining PCF.
262 citations
TL;DR: In this paper, the phase matching between a plasmon and a core mode can be enforced by introducing air-filled microstructures into the fiber core, where the effective refractive index can be lowered to match that of a plasmus by introducing a small central hole into the fibre core.
Abstract: Design strategies for microstructured-optical-fiber (MOF-) based surface-plasmon-resonance (SPR) sensors are presented. In such sensors, plasmons on the inner surface of the large metallized channels containing analyte can be excited by a fundamental mode of a single-mode microstructured fiber. Phase matching between a plasmon and a core mode can be enforced by introducing air-filled microstructures into the fiber core. Particularly, in its simplest implementation, the effective refractive index of a fundamental mode can be lowered to match that of a plasmon by introducing a small central hole into the fiber core. Resolution of the MOF-based sensors is demonstrated to be as low as 3×10−5 RIU, where RIU means refractive index unit. The ability to integrate large-size microfluidic channels for efficient analyte flow together with a single-mode waveguide of designable modal refractive index is attractive for the development of integrated highly sensitive MOF-SPR sensors operating at any designable wavelength.
261 citations
TL;DR: It is demonstrated that by judicious design of the photonic crystal reflector, the effective refractive index of the core mode can be made considerably smaller than that of thecore material, thus enabling efficient phase matching with a plasmon, high sensitivity, and high coupling efficiency from an external Gaussian source, at any wavelength of choice from the visible to near-IR.
Abstract: The concept of photonic bandgap fiber-based surface plasmon resonance sensor operating with low refractive index analytes is developed. Plasmon wave on the surface of a thin metal film embedded into a fiber microstructure is excited by a leaky Gaussian-like core mode of a fiber. We demonstrate that by judicious design of the photonic crystal reflector, the effective refractive index of the core mode can be made considerably smaller than that of the core material, thus enabling efficient phase matching with a plasmon, high sensitivity, and high coupling efficiency from an external Gaussian source, at any wavelength of choice from the visible to near-IR. To our knowledge, this is not achievable by any other traditional sensor design. Moreover, unlike the case of total internal reflection waveguide-based sensors, there is no limitation on the upper value of the waveguide core refractive index, therefore, any optical materials can be used in fabrication of photonic bandgap fiber-based sensors. Based on numerical simulations, we finally present designs using various types of photonic bandgap fibers, including solid and hollow core Bragg fibers, as well as honeycomb photonic crystal fibers. Amplitude and spectrum based methodologies for the detection of changes in the analyte refractive index are discussed. Furthermore, sensitivity enhancement of a degenerate double plasmon peak excitation is demonstrated for the case of a honeycomb fiber. Sensor resolutions in the range 7 * 10(-6) -5 * 10(-5) RIU were demonstrated for an aqueous analyte.
260 citations
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TL;DR: A comparison with similar systems in bulk format shows that the random fiber laser presents an efficiency that is at least 2 orders of magnitude higher than the classical random laser system operating in the incoherent feedback regime.
Abstract: We investigate the effects of two-dimensional confinement on the lasing properties of a classical random laser system operating in the incoherent feedback (diffusive) regime. A suspension of 250 nm rutile (TiO2) particles in a rhodamine 6G solution was inserted into the hollow core of a photonic crystal fiber generating the first random fiber laser and a novel quasi-one-dimensional random laser geometry. A comparison with similar systems in bulk format shows that the random fiber laser presents an efficiency that is at least 2 orders of magnitude higher.
256 citations
TL;DR: Investigation of the strain and temperature characteristics of the two MFPIs with an identical cavity length show that the strain sensitivity of the PCF- based MFPI is smaller than that of the SMF-based M FPI due to their different waveguide structures, while the twoMFPIs have close temperature sensitivities due to the similar host materials.
Abstract: Micro Fabry-Perot (F-P) interferometers (MFPIs) are machined in a single-mode fiber (SMF) and a photonic crystal fiber (PCF) by using a near-infrared femtosecond laser, respectively. The strain and temperature characteristics of the two MFPIs with an identical cavity length are investigated and the experimental results show that the strain sensitivity of the PCF-based MFPI is smaller than that of the SMF-based MFPI due to their different waveguide structures, while the two MFPIs have close temperature sensitivities which are much smaller than that of an in-line SMF etalon sensor reported previously. These MFPIs in silica fibers are compact, stable, inexpensive, capable for mass-production and easy fabrication, offering great potentials for wide sensing applications.
TL;DR: The experimental results show that the wavelength separation between selected resonances allows the measurement of the refractive index of the medium surrounding the fiber for values between 1.25 and 1.44 with an accuracy approaching 1x10(-4).
Abstract: Short-period fiber Bragg gratings with weakly tilted grating planes generate multiple strong resonances in transmission. Our experimental results show that the wavelength separation between selected resonances allows the measurement of the refractive index of the medium surrounding the fiber for values between 1.25 and 1.44 with an accuracy approaching 1x10(-4). The sensor element is 10 mm long and made from standard single-mode telecommunication grade optical fiber by ultraviolet light irradiation through a phase mask.
TL;DR: Single-walled carbon nanotubes have a fast saturable absorption over a broad wavelength range, and the demonstrated technique is an extremely simple and inexpensive method for making fiber-integrated, saturable absorbers for passive modelocking of fiber lasers.
Abstract: Optical radiation propagating in a fiber is used to deposit commercially available, single-walled carbon nanotubes on cleaved optical fiber end faces and fiber connectors. Thermophoresis caused by heating due to optical absorption is considered to be a likely candidate responsible for the deposition process. Single-walled carbon nanotubes have a fast saturable absorption over a broad wavelength range, and the demonstrated technique is an extremely simple and inexpensive method for making fiber-integrated, saturable absorbers for passive modelocking of fiber lasers. Pulse widths of 247 fs are demonstrated from an erbium-doped fiber laser operating at 1560 nm, and 137 fs pulses are demonstrated from an amplified Yb-doped fiber laser at 1070 nm.
TL;DR: In this article, the authors report a highly sensitive (∼2.8pm∕μe) wavelength-encoded strain sensor made from a piece of photonic crystal fiber (PCF) spliced to standard fibers.
Abstract: The authors report a highly sensitive (∼2.8pm∕μe) wavelength-encoded strain sensor made from a piece of photonic crystal fiber (PCF) spliced to standard fibers. The authors intentionally collapse the PCF air holes over a short region to enlarge the propagating mode of the lead-in fiber which allows the coupling of only two modes in the PCF. The transmission spectrum of the interferometer is stable and sinusoidal over a broad wavelength range. The sensor exhibits linear response to strain over a large measurement range, its temperature sensitivity is very low, and for its interrogation a battery-operated light emitting diode and a miniature spectrometer are sufficient.
TL;DR: The low propagation loss of an extruded complex bismuth glass fiber demonstrates the potential of this advanced extrusion technique for the fabrication of novel soft glass and polymer microstructured fiber designs.
Abstract: We report a significant advance in preform extrusion and die design, which has allowed for the first time the fabrication of complex structured preforms using soft glass and polymer billets. Structural preform distortions are minimized by adjustment of the material flow within the die. The low propagation loss of an extruded complex bismuth glass fiber demonstrates the potential of this advanced extrusion technique for the fabrication of novel soft glass and polymer microstructured fiber designs.
TL;DR: Enhanced Kerr nonlinear effects in tapered highly nonlinear As2Se3 chalcogenide fibre with 1.2 mum waist diameter are experimentally demonstrated.
Abstract: We experimentally demonstrate enhanced Kerr nonlinear effects in highly nonlinear As2Se3 chalcogenide fiber tapered down to subwavelength waist diameter of 1.2 µm. Based on self phase modulation measurements, we infer an enhanced nonlinearity of 68 W-1m-1. This is 62,000 times larger than in standard silica singlemode fiber, owing to the 500 times larger n2 and almost 125 times smaller effective mode area. We also consider the potential to exploit the modified dispersion in these tapers for ultra-low threshold supercontinuum generation.
TL;DR: It is shown that it is possible to engineer two-photon states with specific spectral correlation ("entanglement") properties suitable for quantum information processing applications, and which allows heralding of single-Photon pure-state wave packets without the need for spectral post filtering.
Abstract: We study theoretically the generation of photon pairs by spontaneous four-wave mixing (SFWM) in photonic crystal optical fiber. We show that it is possible to engineer two-photon states with specific spectral correlation ("entanglement") properties suitable for quantum information processing applications. We focus on the case exhibiting no spectral correlations in the two-photon component of the state, which we call factorability, and which allows heralding of single-photon pure-state wave packets without the need for spectral post filtering. We show that spontaneous four wave mixing exhibits a remarkable flexibility, permitting a wider class of two-photon states, including ultra-broadband, highly-anticorrelated states.
TL;DR: Experimental results show that smaller core diameter graded-index fibers display greater strain-induced peak wavelength shifts than larger core diameter fibers.
Abstract: We report a low-loss, low-cost high-sensitivity all-fiber strain and temperature sensor based on mode interference in graded-index multimode fibers. Blueshifts with strain and temperature sensitivities of 18.6 pm/microstrain and 58.5 pm/ degrees C have been observed. Experimental results show that smaller core diameter graded-index fibers display greater strain-induced peak wavelength shifts than larger core diameter fibers.
TL;DR: Selective coating of MOFs with metal is demonstrated and used to fabricate an in-fiber absorptive polarizer for microstructured optical fibers.
Abstract: An interesting feature of microstructured optical fibers (MOFs) is that their properties can be adjusted by filling or coating of the holes. Some applications require selective filling or coating, which has proved experimentally demanding. We demonstrate selective coating of MOFs with metal and use it to fabricate an in-fiber absorptive polarizer.
TL;DR: A novel approach of making large effective area laser fiber with higher threshold for the stimulated Brillouin scattering (SBS) using Al/Ge co-doping in the fiber core using an Yb-doped double clad fiber fabricated by the OVD process.
Abstract: We propose a novel approach of making large effective area laser fiber with higher threshold for the stimulated Brillouin scattering (SBS) using Al/Ge co-doping in the fiber core. The increased SBS threshold is achieved by reducing the acoustic-optic overlap integral while keeping the optical refractive index profile with a step structure. The manipulation of the overlap integral is done by adjusting the relative doping level between Al2O3 and GeO2 in the core. The mechanism is validated by detailed examples of numerical modeling. An Yb-doped double clad fiber with the core co-doped with Al2O3 and GeO2 was fabricated by the OVD process. Measured acoustic velocity profile using a scanning acoustic microscope verified that the acoustic velocity in the fiber core changes with the design. An amplifier utilizing the fiber demonstrated that the proposed fiber yielded 6 dB higher SBS threshold than a fiber without using the co-doping scheme.
Patent•
29 Jun 2007
TL;DR: In this article, rare earth doped glass compositions that may be used in optical fiber and rods having large core sizes are described, where the index of refraction of the glass may be substantially uniform and may be close to that of silica.
Abstract: Various embodiments described herein include rare earth doped glass compositions that may be used in optical fiber and rods having large core sizes. Such optical fibers and rods may be employed in fiber lasers and amplifiers. The index of refraction of the glass may be substantially uniform and may be close to that of silica in some embodiments. Possible advantages to such features include reduction of formation of additional waveguides within the core, which becomes increasingly a problem with larger core sizes.
TL;DR: Numerical result shows that very high modal birefringence with a magnitude of the order of 10(-2) around 1550 nm has been obtained and large normal dispersion appears over a wide range of wavelengths in both orthogonal polarizations.
Abstract: We propose a novel polarization-maintaining index-guiding photonic crystal fiber (PCF). It is composed of a solid silica core and a cladding with squeezed-hexagonal-lattice elliptical air holes. Using a full-vector finite-element method, we study the modal birefringence of the fundamental modes in such PCFs. Numerical result shows that very high modal birefringence with a magnitude of the order of 10−2 around 1550 nm has been obtained. Furthermore, large normal dispersion appears over a wide range of wavelengths in both orthogonal polarizations.
TL;DR: A three dimensional fan-out device has been fabricated using ultrafast laser inscription that allows each core of a multicore fibre to be addressed individually by a single mode fiber held in an FVA.
Abstract: A fan-out device has been fabricated using ultrafast-laser waveguide-inscription that enables each core of a multicore optical fiber (MCF) to be addressed by a single mode fiber held in a fiber V-groove array (FVA). By utilizing the unique three-dimensional fabrication capability of this technique we demonstrate coupling between an FVA consisting of a one-dimensional array of fibers and an MCF consisting of a two-dimensional array of cores. When coupled to all cores of the MCF simultaneously, the average insertion loss per core was 5.0 dB in the 1.55 mum spectral region. Furthermore, the fan-out exhibited low cross-talk and low polarization dependent loss.
TL;DR: In this article, the authors consider the main factors determining the oscillation spectral range of cladding-pumped ytterbium-doped fiber lasers and the results obtained for lasers emitting at various wavelengths.
Abstract: In this brief review we consider the main factors determining the oscillation spectral range of cladding-pumped ytterbium-doped fiber lasers (YDFLs) and the results obtained for lasers emitting at various wavelengths. Like erbium-doped fiber amplifiers we suggest dividing the oscillation spectral range of YDFLs into three bands, namely: convenient (C-band), short (S-band), and long (L-band). Polymer-coated double-clad fibers with the inner cladding having a size of more than 100 μm allows one to get efficient operation in the convenient range (C-band): 1060 - 1130 nm. To get an oscillation within the S-band (976 - 980 nm and 1020 - 1060 nm) it is necessary to use active fibers with a small square of the inner cladding. Heating of the active fiber gives the possibility to get lasing within the L-band λ > 1130 nm). Another way to get an emission in this spectral range is by the application of long-wave pumping by a C-band YDFL. Also, we indicate some features that require further study.
TL;DR: In this article, the authors presented highly sensitive refractometers based on a long-period grating in a large mode area PCF with a maximum sensitivity of 1500 nm/RIU at a refractive index of 1.33.
Abstract: We present highly sensitive refractometers based on a long-period grating in a large mode area PCF. The maximum sensitivity is 1500 nm/RIU at a refractive index of 1.33, the highest reported for any fiber grating. The minimal detectable index change is $2\times 10^{-5}$. The high sensitivity is obtained by infiltrating the sample into the holes of the photonic crystal fiber to give a strong interaction between the sample and the probing field.
TL;DR: A photonic device, a plasmonic optical antenna fiber probe, is proposed that can potentially be used for in-situ chemical and biological detection and surface-enhanced Raman scattering.
Abstract: We present a systematic study of optical antenna arrays, in which the effects of coupling between the antennas, as well as of the antenna length, on the reflection spectra are investigated and compared. Such arrays can be fabricated on the facet of a fiber, and we propose a photonic device, a plasmonic optical antenna fiber probe, that can potentially be used for in-situ chemical and biological detection and surface-enhanced Raman scattering.
Book•
01 Jan 2007
TL;DR: In this paper, the authors proposed a model for doped-fiber amplifiers based on honeycomb and cobweb PCFs and showed the phase-matching condition in triangular PCFs.
Abstract: Preface Acknowledgements Introduction 1 Basics of photonic crystal fibers 11 From conventional optical fibers to PCFs12 Guiding mechanism 121 Modified total internal reflection 122 Photonic bandgap guidance 13 Properties and applications 131 Solid-core fibers 132 Hollow-core fibers 14 Loss mechanisms 141 Intrinsic loss 142 Leakage loss 143 Bending loss 15 Fabrication process 151 Stack-and-draw technique 152 Extrusion fabrication process 153 Microstructured polymer optical fibers 154 OmniGuide fibers 16 Photonic crystal fibers in the market Bibliography 2 Guiding properties 21 Square-lattice PCFs 211 Guidance 212 Cut-off 22 Cut-off of large mode area triangular PCFs 23 Hollow-core modified honeycomb PCFs 231 Guidance and leakage 232 Birefringence Bibliography 3 Dispersion properties 31 PCFs for dispersion compensation 32 Dispersion of square-lattice PCFs 33 Dispersion-flattened triangular PCFs 331 PCFs with modified air-hole rings 332 Triangular-core PCFs Bibliography 4 Nonlinear properties 41 Supercontinuum generation 411 Physics of supercontinuum generation 412 Highly nonlinear PCFs 413 Dispersion properties and pump wavelength 414 Influence of the pump pulse regime 415 Applications 42 Optical parametric amplification 421 Triangular PCFs for OPA Dispersion and nonlinear properties 422 Phase-matching condition in triangular PCFs Optical parametric gain in triangular PCFs 43 Nonlinear coefficient in hollow-core PCFs Bibliography 5 Raman properties 51 Raman effective area and Raman gain coefficient 52 Raman properties of triangular PCFs 521 Silica triangular PCFs 522 Tellurite triangular PCFs 523 Enlarging air-hole triangular PCFs 53 Raman properties of honeycomb PCFs 54 PCF Raman amplifiers 541 Model for PCF Raman amplifiers 542 Triangular PCF Raman amplifiers 55 Impact of background losses on PCF Raman amplifiers 56 Multipump PCF Raman amplifiers Bibliography 6 Erbium-doped fiber amplifiers 61 Model for doped-fiber amplifiers 62 EDFAs based on honeycomb and cobweb PCFs 63 EDFAs based on triangular PCFs Bibliography A Finite Element Method A1 Formulation A2 PCF parameter evaluation Bibliography
TL;DR: In this article, the authors present the recent results of their highly efficient directly diode-pumped Tm3+doped silica and Ho3+-doped fiber lasers.
Abstract: We review our recent work in high-power 2-mum fiber laser development, and present the recent results of our highly efficient directly diode-pumped Tm3+-doped silica and Ho3+-doped silica fiber lasers. We quantify the values of the dopant concentrations in the fibers used to construct the 2-mum fiber lasers, and present a more comprehensive assessment of fiber laser performance against dopant concentration.
TL;DR: In this article, a hollow core photonic crystal fiber was modified to allow for filling of only the core with a liquid and its use for detection of surface enhanced Raman scattering from molecules in solution with silver nanoparticles.
Abstract: This letter reports on a hollow core photonic crystal fiber that is modified to allow for filling of only the core with a liquid and its use for detection of surface enhanced Raman scattering from molecules in solution with silver nanoparticles. Both experimental demonstration and theoretical simulation are presented and discussed. The developed sensor is tested in the detection of rhodamine 6G, human insulin, and tryptophan with good sensitivity (10−4–10−5M) due to enhanced interaction volume.
TL;DR: It is demonstrated by numerical simulation that the general features of the loss spectrum of photonic crystal fibres (PCF) with a kagome structure can be explained by simple models consisting of thin concentric hexagons or rings of glass in air.
Abstract: We demonstrate by numerical simulation that the general features of the loss spectrum of photonic crystal fibres (PCF) with a kagome structure can be explained by simple models consisting of thin concentric hexagons or rings of glass in air. These easily analysed models provide increased understanding of the mechanism of guidance in kagome PCF, and suggest ways in which the high-loss resonances in the loss spectrum may be shifted.